Electropolishing and/or electroplating apparatus and methods

ABSTRACT

In one aspect of the present invention, exemplary apparatus and methods are provided for electropolishing and/or electroplating processes for semiconductor wafers. One exemplary apparatus includes a cleaning module having an edge clean assembly ( 930 ) to remove metal residue on the bevel or edge portion of a wafer ( 901 ). The edge cleaning apparatus includes a nozzle head ( 1030 ) configured to supply a liquid and a gas to a major surface of the wafer, and supplies the gas radially inward of the location the liquid is supplied to reduce the potential of the liquid from flowing radially inward to the metal film formed on the wafer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority of earlier filed provisionalapplications U.S. Application No. 60/372,542, entitled “MAINFRAMES FORELECTROPOLISHING AND/OR ELECTROPLATING AND/OR ELECTROPLATING ASSEMBLY,”filed on Apr. 14, 2002; No. 60/379,919, entitled “END EFFECTOR SEAL,”filed on Apr. 8, 2002; No. 60/370,955, entitled “METHOD AND APPARATUSFOR WAFER CLEANING,” filed on Apr. 8, 2002; No. 60/372,566, entitled“METHOD AND APPARATUS FOR ELECTROPOLISHING AND/OR ELECTROPLATING,” filedon Apr. 14, 2002; No. 60/370,956, entitled “METHOD AND APPARATUS FORDELIVERING LIQUID,” filed on Apr. 8, 2002; No. 60/370,929, entitled“METHOD AND APPARATUS FOR LEVELING WAFER,” filed on Apr. 8, 2002; No.60/372,567, entitled “METHOD AND APPARATUS FOR ELECTROPOLISHING METALFILM ON SUBSTRATE,” filed on Apr. 14, 2002; and No. 60/390,460, entitled“ELECTROPLATING APPARATUS,” filed on Jun. 21, 2002, all of which areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field

This invention relates generally to semiconductor processing apparatusand methods, and more particularly to electropolishing and/orelectroplating apparatus and methods for electropolishing and/orelectroplating conductive layers on semiconductor devices.

2. Description of the Related Art

Semiconductor devices are manufactured or fabricated on semiconductorwafers using a number of different processing steps to create transistorand interconnection elements. To electrically connect transistorterminals associated with the semiconductor wafer, conductive (e.g.,metal) trenches, vias, and the like are formed in dielectric materialsas part of the semiconductor device. The trenches and vias coupleelectrical signals and power between transistors, internal circuit ofthe semiconductor devices, and circuits external to the semiconductordevice.

In forming the interconnection elements the semiconductor wafer mayundergo, for example, masking, etching, and deposition processes to formthe desired electronic circuitry of the semiconductor devices. Inparticular, multiple masking and etching steps can be performed to forma pattern of recessed areas in a dielectric layer on a semiconductorwafer that serve as trenches and vias for the interconnections. Adeposition process may then be performed to deposit a metal layer overthe semiconductor wafer thereby depositing metal both in the trenchesand vias and also on the non-recessed areas of the semiconductor wafer.To isolate the interconnections, such as patterned trenches and vias,the metal deposited on the non-recessed areas of the semiconductor waferis removed.

Conventional methods of removing the metal film deposited on thenon-recessed areas of the dielectric layer on the semiconductor waferinclude, for example, chemical mechanical polishing (CMP). CMP methodsare widely known and used in the semiconductor industry to polish andplanarize the metal layer within the trenches and vias with thenon-recessed areas of the dielectric layer to form interconnectionlines.

CMP methods, however, may have deleterious effects on the underlyingsemiconductor structure because of the relatively strong mechanicalforces involved. For example, as interconnection geometries move to 0.13microns and below, there can exist a large difference between themechanical properties of the conductive materials, for example copperand the low k films used in typical damascene processes. For instance,the Young Modulus of a low k dielectric film may be less than one tenthof the magnitude of copper. Consequently, the relatively strongmechanical force applied on the dielectric films and copper in a CMPprocess, among other things, can cause stress related defects on thesemiconductor structure that include delamination, dishing, erosion,film lifting, scratching, or the like.

New processing apparatus and techniques are therefore desired to depositand polish metal layer. For example, a metal layer may be removed ordeposited from a wafer using an electropolishing or electroplatingprocess. In general, in an electropolishing or electroplating processthe portion of the wafer to be polished or plated is immersed within anelectrolyte fluid solution and an electric charge is applied to thewafer. These conditions result in copper being deposited or removed fromthe wafer depending on the relative charge applied to the wafer.

BRIEF SUMMARY OF THEINVENTION

One aspect of the present invention relates to an exemplary apparatusand method for electropolishing and/or electroplating a conductive filmon a wafer. The exemplary apparatus includes various processing modulessuch as cleaning modules, processing modules, alignment modules, as wellas various apparatus for carrying out the processes of the differencemodules such as robotics, end effectors, liquid delivery systems, andthe like.

Another aspect of the present invention includes various apparatus andprocessing methods. One exemplary apparatus includes a cleaning modulehaving a wafer edge clean assembly to remove metal residue on the bevelor outer portion of a major surface of a wafer. The edge cleaningapparatus includes a nozzle head configured to supply a liquid and a gasto a major surface of the wafer. The nozzle supplies the liquid in aregion adjacent an outer edge of the major surface of the wafer, andsupplies the gas radially inward relative to the location the liquid issupplied. Directing the gas to the wafer surface at a location radiallyinward of the location the liquid is supplied may reduce the potentialof the liquid flowing radially inward on the wafer to a metal layerformed thereon.

The present invention is better understood upon consideration of thedetailed description below in conjunction with the accompanying drawingsand claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary semiconductor processing assembly thatmay be used to electropolish and/or electroplate semiconductor wafers;

FIG. 2 illustrates a robot including an exemplary end effector fortransferring semiconductor wafers;

FIG. 3 illustrates a plan view of an exemplary end effector;

FIGS. 4A and 4B illustrate plan and cross-sectional views of anexemplary end effector;

FIG. 5 illustrates a plan view of an exemplary end effector;

FIG. 6 illustrates a plan view of an exemplary end effector;

FIG. 7 illustrates a plan view of an exemplary end effector;

FIG. 8 illustrates a side view of an exemplary vacuum cup;

FIG. 9A illustrates an exemplary cleaning chamber module with a domecover;

FIG. 9B illustrates a partial interior view of a cleaning chambermodule;

FIG. 9C illustrates an exploded view of cleaning chamber module withdetails of cleaning nozzles;

FIGS. 10A and 10B illustrate a top view and side view of an exemplaryedge clean assembly;

FIGS. 11A-11H illustrate various views of an exemplary nozzle headincluded as a part of a bevel clean assembly;

FIG. 12 illustrates an exploded view of an exemplary chuck motorassembly included as part of a cleaning chamber module;

FIG. 13 illustrates an exploded view of a cleaning chamber windowincluded in a cleaning chamber module;

FIG. 14 illustrates an exploded view of an exemplary optical sensorincluded in a cleaning chamber module;

FIG. 15 illustrates an exemplary method for determining proper placementof a wafer in a chuck;

FIGS. 16A-16C and 17A-17C illustrate exemplary wafer cleaning processes;

FIG. 18 illustrates an exploded view of an exemplary process chamberassembly;

FIG. 19 illustrates an exploded view of an exemplary process drivesystem, which may be included in the process chamber assembly embodiedin FIG. 18;

FIG. 20 illustrates an exemplary nozzle with an energy enhancementelement;

FIG. 21 illustrates an exploded view of an exemplary electroplatingapparatus;

FIG. 22 illustrates an exploded view of the exemplary plating showerhead assembly shown in FIG. 21;

FIG. 23 illustrates an exploded view of an exemplary plating shower headfor 300 mm wafers;

FIG. 24 illustrates an exploded view of an exemplary plating shower headfor 200 mm wafers;

FIGS. 25A-25E illustrate various views of the shower head shown in FIGS.22-24;

FIGS. 26A and 26B illustrate a top view and cross-sectional view of anexemplary leveling tool and wafer chuck;

FIG. 26C illustrates a cross-sectional view of an exemplary sensor shownin FIGS. 26A and 26B; and

FIG. 27 illustrates an exemplary view of a software panel for a levelingtool.

DETAILED DESCRIPTION

In order to provide a more thorough understanding of the presentinvention, the following description sets forth numerous specificdetails, such as specific materials, parameters, and the like. It shouldbe recognized, however, that the description is not intended as alimitation on the scope of the present invention, but is insteadprovided to enable a better description of the exemplary embodiments.

I. Exemplary Electropolishing and/or Electroplating Assembly:

A first aspect of the invention includes an exemplary electropolishingand/or electroplating assembly for processing semiconductor wafers. Inone example, an apparatus for processing one or more semiconductorwafers may include a module for storing wafers, two or more verticallystacked processing modules for electropolishing the wafer orelectroplating the wafer, a cleaning module, and a robot (with an endeffector or the like) for transferring the wafer. The apparatus may bedivided into two or more sections characterized by separate frames. Ingeneral the robot transfers the wafer between the module for storing thewafer, the processing module, and the cleaning module to perform adesired process on the wafer. Additionally, various other modules andfeatures may be included for the processing of semiconductor wafers aswill be described.

FIG. 1 illustrates an exploded view of an exemplary electropolishingand/or electroplating assembly 100. In this example, the assembly 100includes a mainframe (backend, “BE”) 108 and frontframe (factoryinterface, “FI”) 132; however, the assembly 100 may be divided intofewer or more sections.

The BE 108 may include an electrical chassis assembly 102, cleaningdrain/process exhaust 104, cleaning module assembly 106, AC controlassembly 110, liquid delivery system (LDS) 112, gas control system (GCS)114, process drain 116, pumps and surge suppressors 118, cabinet exhaust120, process tank 122, liquid filters 124, liquid containment tray 126,and double containment area 128, process module assembly 130.

The FI 132 may include a wafer pre-aligner 134, front panels 136, lighttower 138, robot frame assembly 140, robot controller 142, emergencymachine off (EMO) button 144, front opening unified pod (FOUP) 146, andfan filter unit 152.

Assembly 100 may be detached into two sections, i.e., the FI 132 and theBE 108, allowing the two sections to be transported separately and bereassembled on site into a single unit. Furthermore, the robot frameassembly 140, which can include robot assembly 147, dry end effector148, wet end effector 149, and robot controller 142, may detach from androll out of the FI 132 during transit or for maintenance, for example.Assembly 100 may therefore be modularized or divided into varioussections to assist in transporting, cleaning, maintenance, and the like.

As shown in FIG. 1, FOUP 146 may include one or more pods for storingwafers. The dry end effector 148 transfers a wafer 150 from any one ofthe pods to the wafer pre-aligner 134. The wafer pre-aligner 134 alignswafer 150 before the wet end effector 149 retrieves the wafer andtransfers it to the process module assembly 130. It should be recognizedthat wafer 150 may be transported between modules by other methods anddevices.

The process module assembly 130 may include one or more racks ofelectropolishing assemblies for polishing wafers, or electroplatingassemblies for plating wafers 131. The electropolishing assemblies orelectroplating assemblies 131 may be stacked vertically to reduce thefootprint of the process module assembly 130. The cleaning moduleassembly 106 can include racks of cleaning chamber modules 107 forcleaning wafers. Similarly, cleaning chamber modules 107 may be stackedvertically. After wafer 150 has been processed for electropolishing orelectroplating, the wet end effector 149 transfers wafer 150 to thecleaning chamber module 107. Dry end effector 148 retrieves wafer 150from cleaning chamber 107 and returns wafer 150 to its pod in FOUP 146.Generally, the “dry” end effector 148 is used when retrieving wafer 150from and returning to a pod in FOUP 146, or from the cleaning chambermodule 107. The “wet” end effector 149 is generally used to retrievewafer 150 after processing because wafer 150 may have residue from theprocessing. Limiting the retrieval of processed wafers with the wet endeffector 149 will reduce the potential for cross contamination betweendry end effector 148 and wet end effector 149 and the wafers they handleand transfer within assembly 100.

An exemplary electropolishing assembly that may be used in conjunctionwith assembly 100 is described in PCT Patent Application No.PCT/US02/36567, entitled ELECTROPOLISHING ASSEMBLY AND METHODS FORELECTROPOLISHING CONDUCTIVE LAYERS, filed on Nov. 13, 2002, which isincorporated in its entirety by reference herein.

As shown in FIG. 1, a majority of the electrical equipment is housed inthe BE 108, particularly, in electrical chassis assembly 102 and ACcontrol assembly 110. The LDS 112 and the GCS 114 are also located inthe BE 108.

The LDS 112 can include supply lines for DI water, and various chemicaland/or electrolyte fluids, which may vary in composition depending onthe particular application and processing modules included in assembly100. The GCS 114 may also include various control valves, sensors, andsupply lines to control and monitor delivery of various chemicals andfluids.

Pumps and surge suppressors 118 pump the process liquid from the processtank 122 to process module assembly 130. Liquid filters 124 may beincluded in the supply lines to filter the process liquid before it goesto the process module assembly 130. After wafer 150 is processed, theprocess liquid may be drained into the process tank 122 through processdrain 116. Any gases, e.g., potentially harmful gases, from processmodule assembly 130 and cleaning module assembly 106 may be exhaustedthrough process exhaust 104. The cleaning drain/process exhaust 104 canalso be used to release DI water or gas from the cleaning moduleassembly 106. The cabinet exhaust 120 can be used to release gasgenerally present inside of the BE 108. FI 132 may include a fan filterunit 152 to provide filtered clean air in FI 132.

The BE 108 may also include liquid containment tray 126 and doublecontainment area 128. The liquid containment tray 126 can be useful incase of an overflow from the process tank 122, or leaks in the supplylines. The liquid containment tray 126 may further include leak sensorsto detect leaks. The double containment area 128 can contain leaks fromsupply lines that are already insulated by external tubing.

The supply lines, pumps and surge suppressors 118, liquid filters 124,liquid containment tray 126, and double containment area 128 maygenerally include materials resistant to acid and corrosion.

BE 108, FI 132, and robot frame assembly 140 can be made of stainlesssteel, preferably grade 316 stainless steel. The robot assembly 147 canbe made of aluminum, stainless steel, or the like. If robot assembly 147includes aluminum or other materials susceptible to corrosion, thesurface of the aluminum portions may be anodized and coated with Teflonor the like to protect them from corrosion. Cleaning module assembly 106can be made of stainless steel, plastic, PVC, PVDF, polyurethane,Teflon, and the like, preferably grade 316 stainless steel. GCS 114 andliquid containment tray 126 can be made of plastic materials, preferablynon-flammable plastics. Process tank 122 can be made of plastics such asPVC, PVDF, Teflon, and the like, preferably PVDF. It should berecognized, however, that other suitable materials or coatings for usein BE 108 and/or FI 132 are contemplated.

An exemplary process for electropolishing or electroplating asemiconductor wafer begins with a pod containing wafers placed in FOUP146. The pod, or door to the pod, is opened to allow robot assembly 147access therein to pick a wafer with end effector 148. Robot assembly 147and dry end effector 148 transfer wafer 150 to wafer pre-aligner 134 toalign wafer 150 for processing. After wafer pre-aligner 134 aligns wafer150, robot assembly 147 picks up wafer 150 from wafer pre-aligner 134using the wet end effector 149, and transfers wafer 150 toelectropolishing or electroplating assembly 131 for processing.

After the electropolishing or electroplating process is completed, robotassembly 147 picks up wafer 150 by using the wet end effector 149, andmoves the wafer into cleaning chamber module 107. After the cleaningprocess is completed, dry end effector 148 picks up wafer 150 andtransfers wafer 150 back to the pod in FOUP 146 for retrieval.

In another exemplary process including multiple wafers and multipleelectropolishing or electroplating assemblies, the exemplary processdescribed above may be applied to a first wafer as simultaneouslysimilar steps are applied to a second wafer, a third wafer, etc.

Various components of assembly 100 will be described in greater detailbelow. Although the exemplary electropolishing and/or electroplatingapparatus has been described with respect to certain embodiments,examples, and applications, it will be apparent to those skilled in theart that various modifications and changes may be made without departingfrom the invention.

II. End Effector Seal

In one aspect of a semiconductor assembly, an exemplary end effectorapparatus and method are described. End effectors are commonly used inwafer fabrication processes for transferring wafers, for example, fromone processing module to another for further processing, cleaning,storage, and the like. An exemplary end effector according to oneembodiment includes a vacuum cup seal to securely hold and transfer asemiconductor wafer. The exemplary end effector may be included within asemiconductor processing assembly, and more specifically, a robotassembly of a semiconductor assembly. The exemplary end effector mayenable a more secure hold of a semiconductor wafer surface and in turnmay transfer the wafer more accurately and reliably to its destination.

FIG. 2 illustrates an exemplary robot assembly for transferringsemiconductor wafers in a processing assembly. Robot assembly includesexemplary end effector 206 associated with the robot for picking up andtransferring wafer 216. End effector 206 creates a vacuum on theunderside of end effector 206 to secure wafer 216 thereto for transfersfrom one module to another. End effector 206 may place or release wafer216 by eliminating the vacuum or increasing the pressure such that theforce of gravity overcomes the seal and wafer 216 is released from endeffector 206. Additionally, end effector 206 may hold the underside ofwafer 216 with a relatively smaller pressure than the environment tohold the wafer 216 thereto against vibration, acceleration duringtransfer, and the like.

FIG. 3 illustrates one side of an exemplary end effector 306 in greaterdetail. As shown in FIG. 3, end effector 306 is coupled to a vacuumsource controlled by vacuum valve 322 and with a pressured nitrogensource controlled by nitrogen valve 320. When vacuum valve 322 is turnedON, the vacuum source is coupled to end effector 306 and will reduce thepressure in vacuum cup 302 to hold wafer 216 to end effector 306. Whenvacuum valve 322 is turned OFF and nitrogen valve 320 is turned ON, endeffector 306 will release wafer 216 from vacuum cup 302 as the pressureis increased within cup 302.

It should be understood that an absolute or near absolute vacuum is notrequired; rather, a reduced pressure relative to the processingenvironment sufficient to hold and secure wafer 216 against gravity,vibrations, acceleration during transfer, and the like is sufficient.Further, gas other than nitrogen, for example, air or the like may beused to introduce gas and increase the pressure when releasing a wafer.

Nitrogen valve 320 may be left ON when a wafer is not being held ortransferred to purge particles and/or prevent acid and the like fromentering vacuum cup 302 or the vacuum passage within end effector 306 bymaintaining the pressure near or greater than the surroundingenvironment pressure within vacuum cup 302.

FIGS. 4A and 4B illustrate a plan view and cross-sectional view of oneexemplary end effector 406, which includes vacuum cup 402, mushroom cap404, groove 405, cut out portions 408 (to reduce weight of endeffector), vacuum passage 412, and screws 416 (for attachment to a robotor the like). End effector 406 may include any suitable material in itsconstruction, such as stainless steel, aluminum, various alloys ormetals, ceramics, plastics, and the like.

As shown in FIGS. 3 and 4A, a vacuum source removes gas through vacuumpassage 412 and aperture 414 located on a major side and near the distalend of end effector 406. Vacuum passage 412 may be formed integral orwithin end effector 406 (as shown) or through a separate passage locatedadjacent to end effector 406, e.g., on the opposite surface of endeffector 406.

With the vacuum or reduced pressure created in vacuum passage 412 awafer positioned adjacent end effector 406 is pulled or forced compliantagainst the vacuum cup 402 to create a temporary seal between theopposing major surface of the wafer and the vacuum cup 402 of endeffector 406. Vacuum cup 402 may have any suitable shape such aselliptical, elongated circle, square, and the like. Vacuum cup 402 fitsover the rim of a mushroom cap 404 and extends above the surface of endeffector 406. Vacuum cup 402 may include an elastomer, silicon rubber,or other suitable material that is generally flexible or compliant tocreate a temporary seal with a wafer without causing damage to the wafersuch as scratching or cracking.

As shown in FIGS. 4A-4B, a shallow groove 405 is formed across themushroom cap 404 for increasing the hold of the vacuum, e.g., to preventthe wafer 416 from plugging aperture 414. The groove 405 separates thetop plane of mushroom cap 404 into two half circles. The shallow groove405 may also be formed as a cross-hair shape, square, circle, or othersuitable shape to improve suction and vacuum of end effector 406 andreduce the potential for aperture 414 from becoming blocked. Mushroomcap 404 may be made out of a similar material as end effector 406 suchas metal or plastic. In one example, mushroom cap 404 is at a similarheight as the distal end of end effector 406 (see FIG. 4B), such that asthe wafer is pulled by vacuum cup 402 the wafer is pulled against the todistal ends and the mushroom cap 404.

FIG. 8 illustrates a cross-section view of a vacuum cup that may beincluded in an exemplary end effector. As shown in FIG. 8, the vacuumcup is generally a cavity formed on one surface of an end effector thatmay include a bottom portion 818 and sidewall 820 slanted generally atangle α. Angle α may vary between 0-180 degrees depending on theparticular application, preferably between 5 and 50 degrees, and morepreferably approximately 30 degrees. Sidewall 820 may extend to a heightH above the surface of the end effector to be compliant and form a sealwith a wafer. With additional reference to FIGS. 4A, 4B, and 8, endeffector 406 will be positioned such that wafer 416 comes in contactwith the edge of sidewall 820 as gas is drawn out from aperture 414through the vacuum passage 410. The vacuum cup 402 will pull and holdwafer 416 by the vacuum created in the cavity of vacuum cup 402. Thepressure difference will create a sufficient force to maintain a holdingforce on wafer 416 greater than the force of gravity on the wafer. Torelease wafer 1016 from the hold of end effector 406, gas (e.g. nitrogenor the like) may be introduced through vacuum passage 410 and throughaperture 414 to increase the pressure within the aperture 414 such thatthe holding force is overcome by gravity.

FIG. 5 illustrates a plan view of another exemplary end effector 506.End effector 506 illustrated in FIG. 5 is similar to that of FIGS. 3,4A, and 4B except that end effector 506 includes three apertures 514 andthree vacuum cups 502. The apertures 514 and vacuum cups 502 may belocated in various positions on the end effector 506, depending on thedesign and particular application of the end effector 506. Further, theshape of an end effector may include any suitable shape, such ashorseshoe, rectangular, circular, pronged including one or more prongs,and the like.

FIG. 6 illustrates a plan view of another exemplary end effector 606.End effector 606 is similar to that of FIGS. 4A and 4B except that endeffector 606 has a plurality of vacuum cups 602, in this instance fivevacuum cups 602, each including an elongated (i.e., not circular)mushroom caps 604. Further, end effector 606 includes a common vacuumpassage positioned adjacent the apertures 614 as opposed to FIG. 5,which includes vacuum passages branched apart for each separate aperture514.

FIG. 7 illustrates a plan view of another exemplary end effector 706.The end effector 706 of FIG. 7 is similar to that of FIGS. 3A and 3Bexcept that one vacuum cup 702 includes a plurality of apertures 714therein. Vacuum cup 702 of this example, is shaped like a horseshoe, butwith similar functionality as vacuum cup 402 and includes severalelongated mushroom caps 704, which are similar to the mushroom caps 604.

Although the exemplary end effector seals have been described withrespect to certain examples and applications, it will be apparent tothose skilled in the art that various modifications and changes may bemade without departing from the invention. For example, various methodsof creating a vacuum within the vacuum cup are contemplated as well asvarious other shapes and configurations of vacuum cups and mushroom capsto create seal when picking and transferring a wafer.

III. Method and Apparatus for Wafer Cleaning

In one exemplary aspect of a semiconductor assembly, an exemplary wafercleaning method and apparatus are described. The exemplary wafercleaning method and apparatus, may clean a wafer of debris or particlesbefore an electropolishing or electroplating process as well as cleanthe wafer of processing liquid after an electropolishing orelectroplating processing step. For example, after an electropolishingprocess the edge or outer region of the major surface of the wafer(often referred to as the “bevel region”) may include copper residue. Itis desirable to etch away this copper residue from the outer region andclean the wafer without damaging the thin metal layer in the innerregion of the wafer. Therefore, in one aspect a cleaning module includesan edge clean assembly to remove metal residue on the outer or edgeportion of a wafer. The edge cleaning apparatus includes a nozzle headconfigured to supply a liquid and a gas to a major surface of the wafer.The nozzle supplies the liquid in the edge region and supplies the gasat the inner edge of the edge to reduce the potential of the liquidflowing radially inward on the wafer to the metal film.

FIGS. 9A-9C illustrate various views of an exemplary cleaning chambermodule for cleaning a wafer. As shown in FIGS. 9A-9C, the exemplarycleaning chamber module may include a dome cover 902, cleaning chamberwindow 904, cylinder cover 906, leak sensor 908, drip pan drain line910, base block 912, drip pan clamp 914, drip pan 916, bottom chamber918, cutout for chuck motor assembly wiring 920, two DI water nozzles922 (backside) and 926 (top), two nitrogen nozzles 924 (backside) and928 (top), edge clean assembly 930, optical sensor 932, nozzle for waferfront side chemical 934, chuck 936, drain plate 938, top chamber 940,exhaust and drain tube 942, nitrogen line 944, edge clean cover 946,nozzle for wafer backside chemical 948, and chuck motor assembly 950. Inaddition to the one nozzle for chemical 934, a cleaning chamber modulecan include one or more nozzles for chemicals.

Wafer 901 may be positioned in the cleaning chamber by an end effector903 or the like. When wafer 901 is determined to be in an acceptableposition on chuck 936 for a cleaning process, the chuck motor assembly950 can rotate chuck 936 and wafer 901 around the axis perpendicular tothe major surfaces of the wafer. As chuck 936 and wafer 901 are rotatingat a rotation speed of about 30 rpm, the DI water nozzles 922 and 926can supply streams of DI water to the top and backside surfaces of wafer901. The DI water can flow past the edge of wafer 901 toward the wall ofthe cleaning chamber and drain through the drain plate 938 and into theexhaust and drain tube 942. To remove the DI water from and to dry wafer901, the chuck motor assembly 950 may increase the rotation speed to2,000 rpm, ±1,000 rpm. The nitrogen nozzles 924 and 928 can then supplystreams of nitrogen (or other suitable gas) to the top and backside ofwafer 901 to further remove DI water from the top and backside of wafer901.

After wafer 901 is washed and dried and the chuck motor assembly 950 isstopped, the edge clean assembly 930 glides into position for edgecleaning. FIGS. 10A-10B illustrate an exemplary wafer edge cleanassembly 930, which may include DI water tube 1006, rod 1010, adapterrod 1008, bracket 1012, screws 1014, air table cylinder 1016, adjustablescrew 1018, flow regulator 1020, compressed air tube 1022, rod clamp1024, acid tube 1026, nitrogen tube 1028, nozzle head 1030, rod wiper1032, nitrogen nozzle 1034, and liquid nozzle 1036. The length of theedge clean assembly 930 may be adjusted for use with 200 mm wafer, 300mm wafer, or other size by adding or removing adapter rod 1008. The gapbetween the top of wafer 901 and the nitrogen nozzle 1034 can be in therange from 0.1 to 10 mm, and the liquid nozzle 1036 can be positionedabove the edge area 1004.

FIGS. 11A-11C illustrate plan, side, and front views respectively ofexemplary nozzle head 1030 included with an edge clean assembly. Asshown in FIGS. 11A-11C, nitrogen nozzle 1034 produces a nitrogen curtain1102 of nitrogen gas near the edge of wafer 901. In an exemplary edgecleaning process, wafer 901 may rotate at a rotation speed ofapproximately 50˜500 rpm, preferably at 200 rpm. Liquid nozzle 1036supplies a stream of chemical to form a thin layer of about 10 mm inwidth on the outer major surface of wafer 901 or edge area 1004. Thechemical removes the metal layer or metal residue, but the chemical mayaccidentally spread toward the center of wafer 901, which may havedeleterious effects on the metal layer. A variety of chemicals can beused to etch the metal residue in edge area 1004. For instance, H₄SO₄ at10% concentration and H₂O₂ at 20% concentration can be used to etchcopper metal from edge area 1004. Also, for increasing etch rates, thechemical solution can be heated to the range of 25° C. to 80° C.

To reduce the potential for the chemical spreading inward from the edge,nitrogen nozzle 1034 supplies or directs a stream of gas, e.g.,nitrogen, to create nitrogen curtain 1102 at the inside edge of the edgearea 1004 to prevent or at least reduce the potential of the chemicalfrom spreading toward the center of wafer 901. After edge area 1004 iscleaned, liquid nozzle 1036 can supply liquid jet 1104 of DI water todilute and/or rinse off the chemical from wafer 901 at the edge area1004. Additionally, in one example, after the edge cleaning process anadditional DI water wash may be performed by using DI water nozzles 922and 926 to clean the top and backside of wafer 901.

When the edge cleaning process is finished, chuck motor assembly 950 canstop rotating chuck 936 and wafer 901, and edge clean assembly 930 canglide back from the edge cleaning position to a rest position.

FIGS. 11D-11E illustrate various views of another exemplary nozzle head1030. The example in FIGS. 11D-11E are similar to that of FIGS. 11A-11Cexcept that the nitrogen nozzle 1034 has a horizontal span 1034 hextended from the nozzle. The horizontal span 1034 h may create anitrogen curtain 3002 that more effectively prevents chemicals from edgenozzle 1036 from spreading towards the center of wafer 901. The distancebetween the horizontal span 1034 h and wafer 901 surface is preferablyin the range of approximately 0.1 mm to 3.0 mm, and more preferablyapproximately 1.5 mm.

FIGS. 11F-11G illustrate various views of another exemplary nozzle head1030. The example in FIGS. 11F-11G is similar to that of FIGS. 11D-11Eexcept that the horizontal span 1034 h is extended from both sides ofthe lower portion of the nozzle.

FIG. 11H illustrates another exemplary nozzle head 1030. The example inFIG. 11H is similar to that of FIGS. 11A-11C except that it has twoliquid nozzles 1036, one for chemical and another for DI water. Separatenozzles may provide improved performance during a DI water rinse, forexample.

FIG. 12 illustrates an exemplary chuck motor assembly 950 that may beincluded in the wafer cleaning apparatus. In this example, chuck motorassembly 950 includes chuck 936, top motor plate 1202, optical sensor1204, shaft sleeve 1206, motor 1208, flag 1210, spacer 1212, centrifugalblock shaft 1214, centrifugal block 1216, and plug 1218.

With reference again to FIGS. 9A, 9B and 10A, to place a wafer 901 onchuck 936 an end effector 903 takes wafer 901 from a process chamber orthe pre-aligner (see FIG. 1) and moves it to the cleaning chamber modulethrough the cleaning chamber window 904 for cleaning. FIG. 13illustrates an exemplary cleaning chamber window 904 that includes innerplate 1302, outer plate 1304, bracket 1306, flow controller 1308,cylinder 1310, cylinder cover 906, and limit sensor 1312. The endeffector 903 loads wafer 901 in chuck 936. The cylinder 1310 can raisethe outer plate 1304 and close the cleaning chamber window 904 to begina wafer cleaning process.

As shown in FIG. 12, exemplary chuck 936 includes base 1220 and threepositioners 1222. Chuck 936 may be modified for 200 mm wafer, 300 mmwafer, or any other wafer size. When the end effector 903 loads wafer901 in chuck 936, wafer 901 is positioned in the chuck 936 by the threepositioners 1222. With reference again to FIGS. 9A-9C, optical sensor932 can detect the position of wafer 901 in chuck 936. To check theerror in wafer positioning, optical sensor 932 directs a beam to the topsurface of wafer 901 as shown in FIG. 15. If end effector 903 positionswafer 901 on the top surface of a positioner 1222, the beam will notfully reflect back to reflective sensor 932. As chuck 936 rotates, thereflectivity may change accordingly. Furthermore, since the distancebetween wafer 901 and reflective sensor 932 changes, the difference orvariance in the reflectivity may be used to verify if wafer 901 isplaced accurately on chuck 936 and the three positioners 1222 or not. Inone example, when wafer 901 is accurately positioned on chuck 936, bythe three positioners 1222, the reflectivity is read betweenapproximately 70˜75% while the chuck is rotating. However, when wafer901 is not positioned accurately, the reflectivity is read betweenapproximately 30˜60%. A misplaced wafer might move out of chuck 936 whenchuck 936 is rotating at high speeds, which may cause wafer 901 to breakinside of the cleaning chamber module.

An exemplary optical sensor 932 is shown in FIG. 14 and may include afitting tube 1402, fitting o-ring 1404, reflective sensor 1406, holder1408, viton o-ring 1410, and holder flange 1412. It should be recognizedthat other suitable optical sensors may be used to determine properpositioning of a wafer in relation to chuck 936. In other examples,optical sensor 932 may be replaced by a non-optical sensor to measurethe surface of a wafer such as a proximity sensor, eddy current sensor,acoustic sensor, and the like.

To prevent wafer 901 from spinning out of chuck 936 by the motion ofrelatively high centrifugal forces during various cleaning processessuch as a drying cycle and the like, chuck positioner 1222 may include acentrifugal block 1216. The centrifugal block 1216 can include a lowerelement (i.e., a weight) that is heavier than the top portion, which isapproximate to the centrifugal block shaft 1214. When chuck 936 isrotating at a rotation speed of about 1,000 rpm or higher, thecentrifugal force will cause the weights in centrifugal blocks 1216 torotate outward. Consequently, the upper portion of centrifugal block1216 moves inward to hold and secure wafer 901 to chuck 936. The weight,length, and the like of positioner 1222 and centrifugal block 1216 maybe varied to change the speed at which the positioner 1222 moves tosecure the wafer. When the chuck motor assembly 950 decelerates orstops, centrifugal block 1216 will return to its upright position due toreduced or zero centrifugal force. In order to secure the wafer, thechuck rotation speed is set in the range of approximately 200˜3,000 rpm,preferably at 2,000 rpm.

FIGS. 16A-16C illustrate an exemplary backside wafer cleaning processand the wafer in relation to positioners 1222 and wafer backsidechemical 948. In an exemplary wafer backside cleaning process, motor1208 oscillates chuck 936 to face the nozzle for wafer backside chemical948 such that the chemicals can be delivered to the backside of wafer901 without splashing the three wafer positioners 1222. Chemicals thatcontact wafer positioner 1222 may splash onto and chemically etch thetop surface of wafer 901, which may cause defects in the structures anddevices formed on wafer 901. The backside chemical 948 may be positionedbetween two positioners 1222 and oscillated between angles β and −β. Thebackside chemicals may cover an area of wafer 901 beyond angles β and −βby directing backside chemical 948 off center by moving backsidechemical 948 between angles −γ and γ as illustrated in FIGS. 16A-16C.

The chemical delivered by chemical 948 will reach the backside of wafer901, and the cleaning time can be in the range of 5˜100 seconds,preferably in 10 seconds. The cleaning process is then repeated for eachone-third of the backside of wafer 901.

FIGS. 17A-17C illustrate another exemplary backside wafer cleaningprocess. The process is similar to that described with reference toFIGS. 16A-16C except that chuck 936 is continuously rotated and backsidechemical 948 is pulsed or timed to be “on” between positioners 1222 and“off” when directed at positioners 1222. Similar to FIGS. 16A-16C,nozzle backside chemical 948 may oscillate ±γ during the process. Asshown in FIGS. 17B and 17C, as chuck 936 rotates counter-clockwisebackside chemical 948 directs liquid to the wafer until angle a₁ whereit is turned off. Liquid is again directed to the backside of the waferat angle a₂.

In another example, to clean the portion of the backside of wafer 901 incontact with positioner 1222, motor 1208 will generate a rotationalmovement with a sufficient level of rotational acceleration such thatwafer 901 will displace from its original position. Therefore, chemicalsdelivered by nozzle for wafer backside chemical 948 can reach theportion of the backside of wafer 901 that had been in contact withpositioner 1222 before the rotational movement. After cleaning theentire surface of the backside of wafer 901, DI water nozzle 922 willsupply streams of DI water to rinse the chemicals on the backside ofwafer 901.

Wafer 901 can go through one final cleaning cycle. As chuck 936 andwafer 901 are rotating at a rotation speed of about 30 rpm, the DI waternozzles 922 and 926 can supply streams of DI water to the top andbackside of wafer 901 simultaneously. To remove the DI water from and todry wafer 901, the chuck rotation speed can be increased to 2,000 rpm,±1,000 rpm. The nitrogen nozzles 924 and 928 can then supply streams ofnitrogen to the top and backside of wafer 901 to remove DI water filmfrom the top and backside of wafer 901.

In light of the above description of exemplary apparatus and methods,exemplary cleaning recipes or sequences may proceed as follows.

Initiate Cleaning:

-   -   a. Home chuck.    -   b. Open outer plate 1302.    -   c. Place wafer 901 on chuck 936.    -   d. Close outer plate 1302.

Front side Cleaning:

-   -   e. Rotate chuck 936 at speed of 10 to 100 rpm, preferably at 50        rpm.    -   f. Deliver DI water from DI water nozzle (top) 926 to the front        side of wafer 901.    -   g. Stop DI water from DI water nozzle (top) 926, then increase        chuck rotation speed to 1,000˜2,000 rpm, preferably 2,000 rpm.    -   h. Deliver nitrogen from nitrogen nozzle (top) 928 to dry the        top surface of wafer 901.    -   i. Stop nitrogen stream and stop chuck rotation.

Edge Cleaning:

-   -   j. Move the edge cleaning assembly 930 from its rest position to        edge cleaning position by powering the air tube cylinder 1016.    -   k. Rotate wafer 901 at the rotation speed of 100˜500 rpm,        preferably at 350 rpm, deliver nitrogen from nitrogen nozzle        1034 through nitrogen tube 1028.    -   l. Deliver edge cleaning chemical from liquid nozzle 1036        through acid tube 1026.    -   m. After the metal on the edge area 1004 is etched away, stop        delivering edge cleaning chemicals.    -   n. Deliver DI water from the liquid nozzle 1036 through DI water        tube 2006.    -   o. After chemicals on edge area 1004 are rinsed away, stop DI        water stream.    -   p. Deliver nitrogen from nitrogen nozzle 1034 through nitrogen        tube 1028.    -   q. Stop chuck rotation and move edge cleaning assembly 930 back        to the rest position.

Backside Cleaning:

-   -   r. Move chuck 936 to backside cleaning position, i.e., the        position where the distance between the nozzle for wafer        backside chemical 948 and the two adjacent positioners 1222 is        equal. Motor 1208 starts to oscillate chuck 936 around the        nozzle for wafer backside chemical 948. The oscillation angle        should be less than 45°±5°. The nozzle for wafer backside        chemical 948 then delivers chemicals to the backside of wafer        901.    -   s. Repeat step r for the second and third sections of wafer 901.        Alternatively, wafer 901 may be rotated continuously in one        direction and backside chemical 948 is pulsed avoid positioners        1222.

Shift Turn Cleaning:

-   -   t. To shift wafer 901 from its position by using high        acceleration speed during a swift turn.    -   u. Repeat step s.    -   v. Repeat steps s through u for the second one-third of wafer        901.    -   w. Repeat steps s through u for the last one-third of wafer 901.    -   x. Deliver DI water through DI water nozzle (backside) 922 to        the backside of wafer 901 and to the front side of wafer 901        through DI water nozzle (top) 926, with wafer rotating at a        rotation speed of about 50 rpm.    -   y. Stop delivering stream of DI water. Rotate chuck 936 at a        rotation speed of about 1,000˜3,000 rpm, preferably at 2,000        rpm, then deliver nitrogen to both front side and backside of        wafer 901.    -   z. Stop delivering stream of nitrogen and stop chuck 936. Open        the cleaning chamber window 904 by lowering the outer plate 1304        with cylinder 1310. End effector 903 will then pick up wafer 901        and move said wafer to the storing pod (not shown).

The above sequence describes one exemplary recipe for wafer cleaning andis not intended to be limiting. There are various alternative methods toclean wafer 901 in accordance with other various aspects of the presentinvention. For example, a second exemplary recipe includes followingsteps a through d as described above to initiate the cleaning process,followed by steps j through q for edge cleaning, and finishing withsteps e through i to clean and dry the front side with DI water andnitrogen gas.

Another exemplary recipe includes: following steps a through d asdescribed above to initiate the cleaning process; followed by steps jthrough q for edge cleaning; continuing with steps r and s to clean thebackside with chemical; steps e through i to clean and dry the frontside using DI water and nitrogen gas; and steps t through z to clean anddry the backside with DI water and nitrogen gas. Additionally, during abackside cleaning process, DI water may be supplied to the top of thewafer to protect the top surface from any of the chemical used duringthe backside etch. Accordingly, it should be apparent to those skilledin the art that various processes are contemplated for cleaningsemiconductor wafers with the exemplary apparatus and methods.

Although the apparatus and methods for cleaning wafers have beendescribed with respect to certain embodiments, examples, andapplications, it will be apparent to those skilled in the art thatvarious modifications and changes may be made without departing from theinvention.

IV. Process Chamber

In another aspect of a semiconductor assembly, a processing chamber isincluded for electropolishing and/or electroplating semiconductorwafers. The exemplary processing chamber is interchangeable withelectropolishing apparatus and electroplating apparatus.

In one exemplary process, a wafer is rotated while a stream of processfluid is directed to a relatively small portion of a major surface ofthe wafer. A nozzle or the like directing the stream of fluid istranslated along a linear direction parallel to the major surface of thewafer, e.g., from the inner to outer radius of the wafer. To increasethe uniformity of plating or polishing a metal layer on the wafer, therotation of the wafer may be varied to create a constant linear velocityof the wafer surface with respect to the incident stream of fluid.Additionally, various exemplary methods for determining a thin filmprofile and electropolishing or electroplating process are described.

FIG. 18 includes an exploded view of an exemplary process chamberassembly according to one embodiment. Exemplary process chamber assemblycan include dynamic shroud 1802, magnetic coupler 1804, shaft 1806,bracket for mounting shaft 1808, splashguard 1810, tube 1812, chambertray 1814, bottom chamber 1816, feed through for optical sensor 1818,plugs 1820, process chamber 1822, manifold 1824, nozzle plate 1826, endpoint detector 1828, nozzle block 1830, side plate 1832, chamber window1834, half moon chamber 1836, gate chuck 1838, and window cylinder 1840.

The exemplary chambers may be used equally well for electropolishingand/or electroplating, but are described generally with regard toelectropolishing processes. When using the present invention forelectroplating, nozzle block 1830, nozzle plate 1826, manifold 1824 anddynamic shroud 1802 may also be used in an electropolishing process.Alternatively, they may be replaced with a concentric circleelectroplating apparatus. An exemplary concentric circle electroplatingapparatus is described in U.S. Pat. No. 6,395,152, entitled METHODS ANDAPPARATUS FOR ELECTROPOLISHING METAL INTERCONNECTIONS ON SEMICONDUCTORDEVICES, filed on Jul. 2, 1999, and U.S. Pat. No. 6,440,295, entitledMETHODS AND APPARATUS FOR ELECTROPOLISHING METAL INTERCONNECTIONS ONSEMICONDUCTOR DEVICES, filed on Feb. 4, 2000, both of which areincorporated in their entireties by reference herein. Further, exemplaryelectropolishing and electroplating processes are described in PCTPatent Application No. PCT/US02/36567, entitled ELECTROPOLISHINGASSEMBLY AND METHODS FOR ELECTROPOLISHING CONDUCTIVE LAYERS, filed onNov. 13, 2002, U.S. Pat. No. 6,391,166, entitled PLATING APPARATUS ANDMETHOD, filed on Jan. 15, 1999, and PCT Patent Application No.PCT/US99/15506, entitled METHODS AND APPARATUS FOR ELECTROPOLISHINGMETAL INTERCONNECTIONS ON SEMICONDEUCTOR DEVICES, filed on Aug. 7, 1999,all of which are hereby incorporated by reference in their entirety.

Further, an exemplary end-point detector and methods are described inU.S. Pat. No. 6,447,668 entitled METHODS AND APPARATUS FOR END-POINTDETECTION, filed on Sep. 10, 2002, and is hereby incorporated byreference in its entirety.

As shown in FIG. 19, the power drive system, which can be included inthe process chamber assembly, can include x-axis flag 1902, x-axis driveassembly 1904, coupling 1906, motor 1908, bracket for z-axis mount 1910,theta drive belt and pulley 1912, theta y-axis reflective sensor 1914,x-axis sensor 1916, theta mount 1918, z-axis universal ball joints 1920,z-drive table assembly 1922, bracket for z-motion mount 1924, thetamotor 1926, theta drive pulley 1928, chuck assembly 1930, lid back coverassembly 1932, x-axis linear bearing 1934, y-axis adjustment thumb screw1936, z-axis plate 1938, top lid 1940, z-axis linear bearings 1942,shafts 1944, x-axis magnet 1946, magnetic disconnect plate 1948, y-axisstage 1950, magnets 1952, and bracket for magnet mount 1954.

An exemplary chuck assembly is described, e.g., in U.S. Pat. No.6,248,222 B1, entitled METHOD AND APPARATUS FOR HOLDING AND POSITIONINGSEMICONDUCTOR WORKPIECES DURING ELECTROPOLISHING AND/OR ELECTROPLATINGOF THE WORKPIECES, filed on Sep. 7, 1999, U.S. patent Ser. No.09/800,990, entitled METHODS AND APPARATUS FOR HOLDING AND POSITIONINGSEMICONDUCTOR WORKPIECES DURING ELECTROPOLISHING AND/OR ELECTROPLATINGOF THE WORKPIECES, filed on Mar. 7, 2001, and U.S. patent Ser. No.09/856,855, entitled METHODS AND APPARTUS FOR HOLDING AND POSITIONINGSEMICONDUCTOR WORKPIECES DURING ELECTROPOLISHING AND/OR ELECTROPLATINGOF THE WORKPIECES, filed on May 21, 2001, all three of which areincorporated in their entireties by reference herein.

As shown in FIG. 18, the process chamber 1822 can include a dynamicshroud 1802 that translates with chuck assembly 1930 and a splashguard1810 to contain process liquid or electrolyte fluid within the chamberarea. An optical sensor cable can be installed through the feed-through1818 for an optical sensor and end point detector 1828, or othercomponents such as sensors to detect leaks in the bottom chamber 1816 orthe chamber tray 1814. Additional plugs 1820 may be used for furtherfeed-throughs.

The exemplary apparatus of FIGS. 18 and 19 includes magnets 1952 toconnect to the x-axis drive magnet mount plate 1946. The chuck assembly1930 can move along the x-direction by gliding on shafts 1944 throughthe x-axis linear bearing 1934. When the exemplary apparatus is not inoperation, e.g., to change processing apparatus or during maintenance,the process drive system can undock from the process chamber assembly.Motor 1908 will rotate an internal screw in the x-axis drive assembly1904 counterclockwise to move forward along the x-direction. The same ornew process drive assembly may dock with the process chamber assembly inthe same fashion. One example includes a safety measure such that ifthere is an object between the process drive system and the chamber, orsomething preventing the x-axis drive assembly 1904 from moving forwardor backward, the magnets 1952 or 1946 will disengage from the x-axisdisconnect plate 1948. The x-axis drive 1904 and motor 1908 will not beable to move the chuck assembly and top lid further; at which point, thex-axis sensor 1916 will recognize the disengagement of x-axis from therest of the process drive system and motor 1908 will power down.

During the installation or periodic maintenance of the exemplaryapparatus, y-axis adjustment thumb-screw 1936 can adjust the position ofchuck assembly 1930 over the dynamic shroud 1802 and nozzle plate 1826along the y-direction.

With reference to both FIGS. 18 and 19, when the exemplary processchamber is used in a process application, the process drive system willbe docked in the process chamber assembly by connecting magnets 1952 onthe process drive system to magnetic coupler 1804 on the process chamberassembly. Window cylinder 1840 raises gate chuck 1838 from half moonchamber 1836 to create an opening in the chamber window 1834. A robot(see FIG. 1) may transfer wafer 1801 from a pre-aligner (see FIG. 1)through the chamber window 1834. Wafer 1801 is loaded into chuckassembly 1930 for an electropolishing and/or electroplating process.

To move chuck assembly 1930 from the load or home position to a positionfor electropolishing or electroplating, the motor in z-drive tableassembly 1922 turns its internal shaft assembly to lower the z-axisplate 1938 from the top of the z-axis linear bearings 1942 until the gapbetween chuck assembly 1930 and the top of nozzle block 1830 is in therange of approximately 0.5 to 10 mm, and preferably 5 mm. Alternatively,if the exemplary process chamber is used for electroplating, the motorin z-drive table assembly 1922 can lower the z-axis plate 1938 from thetop of the z-axis linear bearings 1942 until the gap between wafer 1801on chuck assembly 1930 and the top of concentric circle apparatus is inthe range of approximately 0.5 to 20 mm, and preferably 5 mm. After afirst metal layer is plated on wafer 1801, z-axis plate 1938 may move upincrementally in accordance with a process recipe for the wafer 1801 foradditional plating.

To polish wafer 1801, the exemplary process chamber removes copper fromthe plated copper wafer 1801 uniformly and incrementally by applyingelectrical current at a different current density for differentlocations on the wafer 1801. The recipe for electrical current and flowof process liquid will be based on the profile of said wafer and otheruser-defined requirements depending on the particular application.User-defined requirements might include the number of runs for largeremovals, the use of larger or smaller nozzles, or thickness of thecopper layers to remain on the wafers. Typically, a wafer measurementmetrology tool measures the thickness profile of the copper plating on asampling of wafers. The measurements will help generate a current ratiotable that can include the current ratio to be used in the polishingprocess at a given set-point on the wafers. The data and the resultingratio table create a metal film thickness profile, which can be furthermodified by user-defined requirements to formulate the profiledthickness of the wafers, and the recipe for electrical current densityand flow rate during a polishing process.

The electrical current density applied to wafer 1801 may vary dependingon the type of removals. For example, to remove a thick metal film onwafer 1801, a higher current will generally be used. To remove a thinmetal film a smaller current will generally be used to enable a morecontrolled and precise removal process.

An exemplary process, or recipe, for electropolishing a wafer includinga relatively thick layer of metal will now be described. The exemplaryrecipe generally entails four or more steps of processing. First, aremoval of a large portion of the thick layer of the metal, e.g.,copper, is performed. Second, the end point detector 1828 measures thereflectivity of the remaining copper layer to determine set-points forfurther polishing at a given location on wafer 1801. This processrecalculates the film thickness profile based on the reflectivityreadings. Third, the process removes relatively thin layers of thecopper in accordance with the new metal film thickness profile. Fourth,the end point detector 1828 measures the reflectivity of the copperlayers to determine if wafer 1801 has been polished to the desiredthickness and/or profile. The third and fourth processes may be repeateduntil wafer 1801 is polished to the desired thickness and/or profile.

It should be recognized, however, that if the end point detector 1828determines that too much copper plating was removed from wafer 1801,e.g., in the initial removal process, the present invention may includea electroplating process wherein certain areas on the surface of thewafer are re-plated with copper. The electroplating process can includea method of reversing the voltage for the nozzle in the nozzle block1830 with a suitable electrolyte fluid such as CuSO₄+H₄SO₄+H₂O or thelike. An exemplary electroplating apparatus and method is described inU.S. Pat. No. 6,391,166 cited previously and incorporated herein.

Exemplary Process Recipe:

Step 1. In order to remove layers of copper on wafer 1801, theta motor1926 rotates chuck assembly 1930 in a constant linear velocity as thechuck assembly 1930 moves along the x-direction. The nozzle in nozzleblock 1830 may direct process liquid to wafer 1801 at a constant flowrate. The rotation speed of theta motor 1926 can be in relation to thecurrent density and the linear travel distance of rotating chuckassembly 1930. The electrical current ratio that is being applied towafer 1801 can also be based on the metal film thickness profile anduser-defined requirements. The exemplary recipe can continuouslyextrapolate new current density between, and new linear velocity at,each data point on the linear travel of rotating chuck assembly 1930.The recipe can be further recalculated using the new current ratio andlinear velocity. Process drive system moves the chuck assembly 1930 backto the start position along the x-direction.

Step 2: End point detector 1828 measures the reflectivity of copperplated surface of wafer 1801, as theta motor 1926 rotates chuck assembly1930 again in a constant linear velocity as the chuck assembly movesback and forth along the x-direction. The present example records thereflectivity of wafer 1801 and the corresponding linear distance of thechuck assembly, at a user defined intervals. The present exampleextrapolates the new data into part of the metal film thickness profile.

Step 3. Repeat Step 1 except the current flow will be adjusted basedupon the reflectivity of end point detector 1828 to wafer 1801 at agiven wafer location of linear distance. A smaller nozzle in nozzleblock 1830 can be used to achieve a more controlled polishing of thecopper plated surface.

Step 4. Repeat Step 2. If the new reflectivity measurements from the endpoint detector 1828 are larger than a pre-set value, repeat Step 3.

During exemplary polishing processes, chuck assembly 1930 may be rotatedin the following three modes:

1) Constant Linear Velocity Mode: $\begin{matrix}{\overset{.}{\vartheta} = \frac{C_{1}}{2\pi\quad R}} & (1)\end{matrix}$

-   -   Where, R is the horizontal distance between nozzle and wafer        center,    -   C₁ is a constant, and    -   {dot over (θ)} is the rotation speed.

In practical control, R=0 gives infinite rotational speed; therefore,equation (1) can be expressed as follows: $\begin{matrix}{\overset{.}{\vartheta} = \frac{C_{1}}{2{\pi( {R + C_{2}} )}}} & (2)\end{matrix}$

Where C₂ is a constant set according to the particular apparatus andapplication.

2) Constant Rotation Speed Mode:{dot over (θ)}=C₃  (3)

Where C₃ is a constant set by process recipe.

3) Constant Centrifugal Force Mode: $\begin{matrix}{\frac{V^{2}}{R} = {C_{4} = \text{Centrifugal~~force}}} & (4)\end{matrix}$

Where, V is the linear velocity, R is the horizontal distance betweennozzle and wafer center, and C₄ is a constant set according to theparticular apparatus and application.

Equation (4) can be rewritten by using V={dot over (θ)}·2πR$\begin{matrix}{\overset{.}{\vartheta} = \frac{\sqrt{C_{4}}}{2\pi\sqrt{R}}} & (5)\end{matrix}$

Again, R=0 gives infinite rotational speed, {dot over (θ)}, inpractical, formula (5) can be written as: $\begin{matrix}{\overset{.}{\vartheta} = \frac{\sqrt{C_{4}}}{2\pi\sqrt{R + C_{5}}}} & (6)\end{matrix}$

Where C₅ is a constant set according to the particular apparatus andapplication.

Horizontal direction or x-direction movement of chuck can be written as:$\begin{matrix}{\overset{.}{R} = \frac{C_{6}}{2\pi\quad R}} & (7)\end{matrix}$

Where {dot over (R)} is the speed of chuck assembly 1930 in x-directionand R=0 gives infinite {dot over (R)}, in practical, formula (7) can bewritten as: $\begin{matrix}{\overset{.}{R} = \frac{C_{6}}{2{\pi( {R + C_{7}} )}}} & (8)\end{matrix}$

Where C₇ is a constant set according to the particular apparatus andapplication.

Although FIGS. 18 and 19 show a process drive system in which the chuckassembly 1930 moves along the x-direction, it should be recognized thatduring a process the nozzle plate 1826 or both the chuck assembly 1930and nozzle plate 1826 can move along the x-direction depending on theparticular application.

FIG. 20 shows an exemplary nozzle 2054 that may be included in theexemplary process chamber assembly. The exemplary nozzle 2054 includesan enhancement energy unit 2080 that may be attached or mechanicallycoupled to the nozzle 2054. The enhancement energy unit 2080 may enhancethe agitation of electrolyte fluid 2081 at the metal film 2004 surfaceto provide a higher polishing rate, better surface finishing, andquality.

In one exemplary nozzle 2054 the energy enhancement energy unit 2080includes an ultrasonic or magnasonic transducer. Electrolyte fluid 2081may be input from side inlet 5200 of nozzle 2054. The frequency of anultrasonic transducer may be in the range of 15 kHz to 100 Mega Hz toagitate the fluid. Ultrasonic transducer can be made of ferroelectricceramics such as barium titanate (LiTaO₃), lead titanate, leadzirconate, and the like. The power of an ultrasonic transducer may be inthe range of 0.01 to 1 W/cm².

In another example, the energy enhancement energy unit 2080 may includea laser. For the similar purpose as described above, a laser can beirradiated on the metal surface during an electropolishing process. Thelaser may be, e.g., a solid state laser such as ruby laser, Nd-glasslaser, or Nd:YAG (yttrium aluminum garnet, Y₃Al₅O₁₂) laser, gas lasersuch as He—Ne laser, CO2 laser, HF laser, or the like. The average powerof the laser may be in the range of 1 watt to 100 watt/cm² forcontinuous mode. In another example, the laser can be operated in pulsemode. The pulse mode laser power can be much higher than the averagemode power as will be recognized by those skilled in the art.

The laser may also detect film thickness of the metal film on wafer1004. In this example, a laser directed to the metal film stimulatesultrasonic waves on metal film. The metal film 2004 thickness may bemeasured through the detected ultrasonic wave during an electropolishingprocess. The thickness of metal film 2004 may be used to control thepolishing rate by changing the current, the nozzle speed in the radiusdirection, and the like.

In another example, the energy enhancement energy unit 2080 may includean infrared light source to anneal the metal film 2004 during apolishing process. The infrared light source can provide additionaloptions to control surface temperature of the metal film duringpolishing. The power of the infrared source may be in the range of 1 wto 100 w/cm². An infrared source may also be used to anneal the metalfilm during a polishing process. The grain size and structure are veryimportant for determining the copper interconnect electromigrationperformance and resistivity. Because the temperature is a factor indetermining the grain size and structure of the metal layer, an infraredsensor can also be used to detect a surface temperature of the metalfilm during a polishing process.

An infrared sensor may also be used to determine the temperature ofmetal film 2004. Monitoring the temperatures allows adjustments of thetemperature during a polishing process with varying infrared sourcepower, changing the current density, and the like.

In another example, the energy enhancement energy unit 2080 may includea magnetic field to focus the polishing current on the metal film 2004during a polishing process. Focusing the polishing current allows forincreased control of the polishing rate profile of the nozzle, which isincreasingly important for relatively large diameter nozzles. Themagnetic field may be generated in the direction of electrolyte flow,i.e., vertical direction to the metal film surface. A magnet andelectric magnet, superconductor coil driving magnet or the like may beused to create and focus the magnetic field.

It should be recognized that other energy sources such as ultraviolet,X-ray, microwave sources, and the like may also be used to enhance theperformance of an electropolishing process as generally described above.

Although the exemplary chamber modules and processes have been describedwith respect to certain embodiments, examples, and applications, it willbe apparent to those skilled in the art that various modifications andchanges may be made without departing from the invention.

V. Electroplating Apparatus and Process

In another aspect of a semiconductor assembly, an electroplatingapparatus and method is included for electroplating semiconductorwafers. In a plating apparatus and process it is generally desired forprocess fluid to be distributed evenly over the surface of the wafer toplate a metal film of uniform thickness. In one exemplary process ashower head for plating apparatus is described that includes a filterblock that impedes an immediate stream of electrolyte fluid anddistributes the process fluid more uniformly through a channel of theshower head prior to emerging from the shower head. Distributing thefluid through the channel more uniformly leads to equal or nearly equalflow rates of electrolyte fluid from each orifice of the shower headassembly to increase the uniformity of the plating process.

FIG. 21 illustrates an exploded view of an exemplary electroplatingapparatus for plating semiconductor wafers 2102. The electroplatingapparatus can include half-moon chamber 2104, stationary shroud 2106,plating shower head assembly 2108, exhaust 2110, liquid inlets 2112,electrolyte fit through 2114, liquid fit through 2116, chamber tray2118, bottom chamber window 2120, bottom chamber 2122, process chamber2124, chamber window 2126, top lid assembly 2130, liquid inlet tubing2132, electrode cable 2134, and shafts 2136. Top lid assembly 2130 maybe functionally similar to the exemplary top lid assembly previouslydiscussed under the heading “Process Chamber.” The stationary shroud2106 covers the wafer chuck (not shown) to prevent electrolyte fromsplashing out of the chamber during the electroplating and spin dryprocess, for example.

As shown in FIG. 21, wafer 2102 is loaded into the electroplatingapparatus through half moon chamber 2104 to the wafer chuck of top lidassembly 2130. To plate copper on wafer 2102, top lid assembly 2130 willlower wafer 2102 and position the wafer above the top of plating showerhead assembly 2108. In one exemplary process of plating, a first metallayer partial deposition is performed while the gap between wafer 2102and plating shower head assembly 2108 is in a range of about 0.1 mm toabout 10 mm, and preferably about 2 mm. Top lid assembly 2130 may raisewafer 2102 an additional 2 mm to 5 mm and a second layer deposition maybe performed where a thicker layer of copper is deposited on the wafer.

Exemplary electroplating processes and sequences are described in U.S.Pat. No. 6,391,166, entitled PLATING APPARATUS AND METHOD, filed on Jan.15, 1999, U.S. patent application Ser. No. 09/837,902, entitled PLATINGAPPARATUS AND METHOD, filed on Apr. 18, 2001, and U.S. patentapplication Ser. No. 09/837,911, entitled PLATING APPARATUS AND METHOD,filed on Apr. 18, 2001, the entire contents of which are incorporatedherein by reference.

FIG. 22 illustrates an exploded view of an exemplary shower headassembly 2108 for a plating process. Shower head assembly 2108 mayinclude outer channel ring 2202, shower head top 2204, and shower head2206. FIGS. 23 and 24 illustrate exploded views of exemplary showerheads configured for electroplating 300 mm wafer and 200 mm waferrespectively. For use with 200 mm wafers, simply replace the 300 mmouter channel ring 2302 with the 200 mm outer channel ring 2402, and the300 mm shower head top 2304 with the 200 mm shower head top 2404. Thus,shower head 2006 can be used for both 300 mm and 200 mm wafers. Withreference to FIG. 24, as the size of wafer decreases from 300 mm to 200mm, the shower head top 2404 may include fewer rings and the outerchannel ring 2402 may be smaller in diameter. It should be recognized,however, that the exemplary shower head may be configured for any sizewafer.

FIG. 25A illustrates an exploded view of an exemplary shower head. Asshown in FIG. 25A, shower head 2206 may include electrode rings 2502,nuts 2504, electrode connectors 2506, electrode outer connectors 2508,small inlet flare fittings 2510, inlet flare fittings 2512, plate filterblocks 2514, shower head base 2516, filter spacers 2518, and platefilter rings 2520. Each electrode ring 2502 is fitted on top of amatching plate filter ring 2520 and locked into place on the shower headbase 2516 by fastening the electrode of electrode ring 2502 with nuts2504, electrode connector 2506 and electrode outer connector 2508. Eachelectrode is attached with an electrode cable 2134 to electrode outerconnector 2508 as shown in FIG. 21. Electrode ring 2502 can be made ofanticorrosive metals or alloys, such as platinum, titanium coated withplatinum, and the like. Shower head base 2516 will have channels forelectrolyte flow from inlet flare fittings 2512 and from small inletflare fittings 2510.

As further seen in FIG. 25A, an inlet flare fitting 2512 can be largerthan the width of a channel in shower head base 2516 and the inlet flarefittings cannot be fasten on the same position for all 7- or 10-rings.In order to fasten the inlet flare fittings to shower head base 2516 andto evenly distribute the tension and weight to the rings, every othersmall inlet flare fitting 2510 or inlet flare fitting 2512 and opposingfilter block 2514 are positioned on an opposite half of the circle (notshown for filter blocks 2514). Similar to inlet flare fitting 2512,electrode ring 2502 fits over plate filter ring 2520 such that theelectrode is positioned on the other half of the circle with every otherelectrode ring.

FIG. 25B illustrates an exploded view of a plate filter ring 2520 andplate filter block 2514 joined together by filter spacers 2518 to form aliquid flow block assembly, with an electrode ring 2502 fitting over theliquid flow block assembly. The exemplary liquid flow block assemblywill be positioned above shower head base 2516 with an inlet flarefitting 2512 beneath and center of each plate filter block 2514 with ano-ring 2530 (not shown). Each plate filter ring 2520 has orifices 2522with a narrow aperture in the center of each orifice. With reference nowto both FIGS. 25A and 25B, as the liquid flow block assembly and anelectrode ring 2502 are fastened to shower head base 2516, a channel isformed between plate filter ring 2520 and the bottom of the shower headbase. Electrolyte fluid will flow in from inlet flare fitting 2512. Theelectrolyte stream will first hit the center of the plate filter block2514 above the inlet and be distributed throughout the channel. As theelectrolyte fluid rises in the channels, the electrolyte will flow outof orifice 2522 uniformly and reach the electrode rings 2502. Theelectrolyte fluid passes the electrode ring 2502, and flows uniformly tothe surface of wafer 2102 through apertures 2524 in nozzle head 2004.

FIG. 25C illustrates the relationship between orifices 2522 and thenozzle head's apertures 2524 on the bottom of shower head 2006. As shownin FIG. 25C and FIG. 22, the shower head top 2004 is stacked over showerhead 2006 such that the apertures 2524 are positioned in between twoorifices 2522. This staggered positioning allows the flow of electrolytediscussed in above to flow more uniformly through each recess on theliquid block flow assembly. As illustrated in the top view of the showerhead in FIG. 25D, the apertures 2524 are disposed around the outer ringon shower head top 2204 (or 2304 or 2404). These apertures 2524, alsoinside of the enclosing rings on the shower head top 2204, may be formedin any shape, such as circle, elongated, and the like depending on theparticular application. With reference to FIG. 24, apertures 2524 may beformed in an elongated circular shape created by forming three roundholes.

Without plate filter block 2514, inlet flare fitting 2512 may deliverelectrolyte directly through one or more apertures above the proximityof the inlet flare fitting, causing disproportionate distribution ofelectrolyte throughout the channel. Since electrolyte is flowing fromone outlet, the liquid pressure of electrolyte can be difficult tocontrol. Using the liquid flow block assembly, the exemplary apparatusmay provide for better control of electrolyte for metal deposition,e.g., copper, because plate filter block 2514 will impede the immediatestream of electrolyte and distribute the electrolyte throughout thechannel. Distributing the electrolyte throughout the channel allowsequal or nearly equal volumes of electrolyte to flow out of each orifice2522 on plate filter ring 2520. As shown in FIG. 25E, electrolyte comesout of electrode outer connectors 2508, through the shower head base2516 and plate filter ring 2520, then around the sides of electrode ring2502 and flows out of the apertures 2524 on shower head top 2004.

Although the exemplary shower head apparatus has been described withrespect to certain embodiments, examples, and applications, it will beapparent to those skilled in the art that various modifications andchanges may be made without departing from the invention.

VI. Method and Apparatus for Leveling Wafer

According to another aspect, a method and apparatus for leveling asemiconductor wafer relative to a processing module such as anelectropolishing or electroplating apparatus. Generally, whileprocessing a wafer it is desired that the wafer be leveled such that themajor surface of the wafer is generally parallel to a level surface of aprocessing chamber or tool. For example, aligning the wafer in theprocessing apparatus increases the uniformity of the polishing orplating processes.

FIGS. 26A and 26B show an exemplary leveling tool 2604 that may be usedto measure the parallelism of wafer 2602 within ±0.001 inch relative tothe processing apparatus, e.g., a processing chamber. As shown in FIGS.26A and 26B, the leveling apparatus generally includes leveling tool2604, ground line 2610, signal lines 1612, control system 2614, andchuck 2616.

An exemplary chuck is described in U.S. Pat. No. 6,248,222 B1, entitledMETHOD AND APPARATUS FOR HOLDING AND POSITIONING SEMICONDUCTORWORKPIECES DURING ELECTROPOLISHING AND/OR ELECTROPLATING OF THEWORKPIECES, filed on Sep. 7, 1999, and U.S. Pat. No. 6,495,007, entitledMETHODS AND APPARATUS FOR HOLDING AND POSITIONING SEMICONDUCTORWORKPIECES DURING ELECTROPOLISING AND/OR ELECTROPLATING OF THEWORKPIECES, filed on Mar. 7, 2001, both of which are incorporated intheir entireties by reference herein.

With reference to FIGS. 26A and 26B, chuck 2616 holds wafer 2602 duringa semiconductor electropolishing and/or electroplating process. In orderto provide for a more uniform process of the electropolishing and/orelectroplating process, wafer 2602 is positioned parallel or nearlyparallel to processing chamber 2630, and in particular with the platinghead or polishing nozzles (not shown) of the processing apparatus.Leveling tool 2604 may be positioned within the process chamber 2630 toprovide increased alignment of the wafer 2602.

Leveling tool 2604 may include three sensors 2606 and correspondingsignal lines 2612. When leveling tool 2604 is placed under chuck 2616and the wafer 2602 is brought down to leveling tool 2604, signal lines2612 (through sensors 2606) provide connection to the control system2614 through a thin metal layer formed on the surface of the wafer 2602.A ground line 2610 from control system 2614 is connected to the wafer2602 metal layer. As sensors 2606 contact the thin metal layer a circuitis completed between the sensors 2606 and the ground line 2610 that maybe measured by controller system 2614.

Additionally, as shown in FIG. 26B, leveling tool 2604 may includesupports 2608 for use in measuring the parallelism of wafer 2602 inchuck 2616 and the polishing nozzles as well as position the levelingtool 2604 near the surface of wafer 2602.

FIG. 26C illustrates a cross-sectional view of an exemplary sensor 2606.Sensor 2606 can include holder 2626, set screws 2618, pin adjustment2620, contact screw 2622, and pin 2624. Signal line 2602 is connected tosensor 2606 through contact screw 2622. Holder 2626, pin adjustment2620, and pin 2624 can be made of metals or alloys, such as stainlesssteel, titanium, tantalum, or gold.

In one exemplary process for measuring the alignment or parallelism ofwafer 2602 in relation to the process tool, chuck 2616 descends towardleveling tool 2604 until the pin 2624 of one of sensors 2606 contactsthe conductive surface of wafer 2602. The contact completes anelectrical circuit that includes signal line 2612, ground line 2610, andcontrol system 2614, and provides a signal to control system 2614. Thecontrol system 2614 determines the distance from the original (home)position of chuck 2616 to the pin's position at the moment of thecontact.

Chuck 2616 continues its descent until the second sensor 2606, and thethird sensor 2606 contact the surface of wafer 2602. Correspondingdistances for both sensor contacts are taken and the measurement processends.

As shown in FIG. 27, the exemplary process may include a softwareinterface, which displays the measured distance in the moment of contactfor each sensor 2606. The interface can also display the location ofsensors 2606. The smaller in the difference between a maximum andminimum distance of the measured distances the closer the wafer 2602 isto being aligned or in a parallel relationship. The data can be used tomake adjustment to chuck 2616 and consequently, position of wafer 2602.After the adjustment is made, the measurement cycle can be repeateduntil the difference between the maximum and minimum of the measureddistances is within design specification such as ±0.001 inch or the likedepending on the particular application.

Although the exemplary wafer alignment methods and systems have beendescribed with respect to certain embodiments, examples, andapplications, it will be apparent to those skilled in the art thatvarious modifications and changes may be made without departing from theinvention.

The above detailed description of various devices, methods, and systemsis provided to illustrate exemplary embodiments and is not intended tobe limiting. It will be apparent to those skilled in the art thatnumerous modifications and variations within the scope of the presentinventions are possible. For example, the different exemplaryelectropolishing and electroplating devices, such as the cleaningchamber, the optical sensors, the liquid delivery system, end-pointdetectors, and the like may be used together in a single processassembly or may be used separately to enhance electropolishing and/orelectroplating systems and methods. Accordingly, the present inventionis defined by the appended claims and should not be limited by thedescription herein.

1. An apparatus for processing one or more semiconductor wafers,comprising: a module for storing a wafer; a plurality of verticallystacked processing modules for at least one of electropolishing thewafer and electroplating the wafer; a cleaning module; and a robot fortransferring the wafer between the module for storing, the processingmodule, and the cleaning module, wherein the apparatus is divided intoat least two sections characterized by separate frames.
 2. The apparatusof claim 1, further including a pre-alignment module to align the waferprior to processing.
 3. The apparatus of claim 1, wherein the robotincludes one or more end effectors for picking and transferring thewafer.
 4. The apparatus of claim 1, wherein the robot is removable byrolling or sliding out from one of the at least two sections.
 5. Theapparatus of claim 1, wherein the robot includes, a first end effectorfor transferring the wafer to the processing modules, and a second endeffector for transferring the wafer from the processing modules.
 6. Theapparatus of claim 1, further including a liquid delivery system fordelivering process liquid to the processing modules.
 7. The apparatus ofclaim 6, wherein the liquid delivery system includes a surge suppressor.8. The apparatus of claim 6, wherein the liquid delivery system includesa controller to modulate a flow rate of the process liquid.
 9. Theapparatus of claim 6, wherein the liquid delivery system is housed in acontainment tray.
 10. The apparatus of claim 6 wherein the apparatusincludes an exhaust to remove gases from the processing modules.
 11. Amethod for at least one of electropolishing and electroplating asemiconductor wafer in a process assembly, comprising: transferring awafer to one of a plurality of stacked processing modules with a firstend effector; electropolishing or electroplating the wafer in theprocessing module; transferring the wafer from the processing module toa cleaning module with a second end effector; and cleaning the wafer inthe cleaning module, wherein the process assembly is divided into atleast two sections characterized by separate frames.
 12. The method ofclaim 11, further wherein transferring the wafer includes using a robotand wherein the robot is configured to slide or roll out of the processassembly.
 13. The method of claim 11, further including deliveringliquid to the processing module through a supply line, wherein a surgesuppressor is associated with the supply line.
 14. The method of claim11, further including removing gases from the processing module throughan exhaust system. 15-137. (canceled)